If your React component renders several sibling elements, say three <p> elements for instance, you would have to wrap them in a <div> because React would only allow components to return a single element. The only problem with this approach is that it leads to a lot of unnecessary DOM structure. Wrapping your elements with <Fragment> is the same idea as wrapping them with a <div>, except there won't be any superfluous DOM elements.
You can read more about fragments here: https://reactjs.org/docs/fragments.html.